1. Field of the Invention
The present invention relates generally to vacuum film-forming technology and more particularly, to a method for forming metallic nitride films, such as titanium nitride (TiN) film and zirconium nitride (ZrN) film, which has the advantage of low manufacturing cost since the manufacturing processes of the method are simple and time-effective.
2. Description of the Related Art
Titanium nitride (hereinafter referred to “TiN”), which is a material commonly used for hard coatings, has the characteristics of excellent hardness ranging from 18 to 21 GPa, stable physical and chemical properties, low resistivity ranging from 18 to 170 μΩ-cm, and good abrasion resistance and corrosion resistance, so that it is extensively used in industry. For instance, TiN is commonly used as a hard coating on a surface of a cutter to minimize the cutter's abrasion so as to extend the cutter's lifetime. In the field of electronic industry, TiN is often used as a diffusion barrier layer. Further, because exhibiting golden color, TiN is often used as a decorative layer coated on the surfaces of clocks, adornments and the like in civil industry,
In addition, zirconium nitride (hereinafter refereed to as “ZrN”) film is also extensively used as decorative coatings because of its color diversity and good corrosion and abrasion resistances. Further, the cutters, working tools and surfaces of dies coated with the ZrN film exhibits the advantaged of improved mechanical properties, decrease of surface abrasion and prolongation of lifetime.
TiN and ZrN films are conventionally formed by physical vapor deposition (PVD). The conventional physical vapor deposition is performed in a high vacuum circumstance, in which argon is served as sputtering gas, nitrogen is used as a reactive gas, and the plasma generated by an electrical field of a direct current power or a radio frequency power bombards a titanium target or a zirconium target such that the titanium or zirconium atoms in the solid target are ejected into the gas phase and reacted and combined with the nitrogen, resulting in that a thin TiN or ZrN film is deposited on a substrate.
Before the gas mixture of argon and nitrogen is introduced into the vacuum chamber, the vacuum chamber has to be pumped down to a base pressure of about 1×10−6 Torr. This requires dedicated vacuum chamber and vacuum pump, and takes a long time, which is about 2 to 3 hours, to proceed with the evacuation; besides, the nitrogen used in the PVD method should be obtained from the purification of air. As a result, the cost of equipment and raw material used for the conventional PVD method is expensive and the manufacturing processes are complicated.